This invention relates to an automatic vacuum packaging apparatus in which the operations of forming bags from a long sheet or strip of plastic film, simultaneously enwrapping articles or commodities to be packaged within the film bags, and sealing the openings of the bags with interiors in the state of a vacuum are continuously and automatically performed.
A revolving type vacuum packaging apparatus for placing meat or the like into bags made of plastic film and sealing the openings of the bags under a vacuum is disclosed, for example, in U.S. Pat. No. 3,958,391. This vacuum packaging apparatus has a plurality of vacuum boxes continuously moving along a circular endless rail, in each of which the opening of a bag containing one or more articles is sealed in the state of a vacuum during one revolution of each vacuum box along the rail. In this vacuum packaging apparatus, each of the operations such as opening and closing the vacuum boxes, adjusting air pressures in the boxes, heating for sealing the openings of the bags made of thermoplastic film and taking the sealed bags out of the vacuum boxes is automatically performed. However, the articles to be packaged cannot be automatically put into the bags, and the bags already containing the articles cannot be automatically fed into the vacuum boxes. That is, these two operations are performed manually, and it is especially difficult for a worker to put the articles such as meat into the bags in a short time.
In order to automatically feed the bags into the vacuum boxes, it is considered to convey each bag with its one open end on a conveyor belt from which the bag is transferred automatically into each vacuum box rotating around a sprocket in synchronism with the movement of each bag. In this case, when the bag is transferred from the belt conveyor into each vacuum box, it should be transferred smoothly. If there is a big difference in height between the conveyor belt and each vacuum box, the bag is apt to be laid on the platform of each vacuum box in an irregular posture. Accordingly, the open end of each bag is not laid on a pillow head in a regular posture thereby undesirably preventing the open end thereof from closing tightly when it is sealed in the vacuum box.